Numerous diphosphonate compounds that have been developed in the past primarily for treatment of bone metabolic disorders have action that suppresses bone destruction. These compounds have been expected to suppress bone destruction during the occurrence of arthritis such as chronic articular rheumatism. Compounds having diphosphonate structures are disclosed in Japanese Unexamined Patent Publication (Kokai) No. 59-42395, Japanese Unexamined Patent Publication (Kokai) No. 2-22285, Japanese Unexamined Patent Publication (Kokai) No. 3-77894 and Japanese Unexamined Patent Publication (Kokai) No. 60-174792. However, these diphosphonate compounds are primarily focused on suppression of bone resorption. Although these compounds are effective as therapeutic drugs for bone metabolic disorders, they are still not adequate in terms of treatment of chronic articular rheumatism. In order for diphosphonate compounds to be able to be used for the treatment of chronic articular rheumatism and similar disorders, a new drug is sought that, in addition to having action that suppresses bone resorption, also simultaneously has even further superior effects including the suppression of Interleukin-1 (abbreviated as IL-1), an inflammatory mediator, and the suppression of cell damage caused by activated nucleophils and macrophages.
IL-1 is known to be a mediator involved in fever and inflammation, and an IL-1 inhibitory agent is expected to be useful as an antiinflammatory agent. However, similar to numerous other cytokines, IL-1 is considered to primarily act locally. Although numerous substances have been reported to suppress IL-1 in vitro, antiinflammatory agents have not yet been developed having action that allows adequate improvement of the disease state by actually suppressing IL-1 in vivo. In addition, invasion of activated neutrophils and macrophages at the site of inflammation are observed during inflammations and so on. Although the active oxygen that is produced by these blood cells has the action known as heterogenous digestion, in cases when such inflammation becomes chronic, it is known that even normal tissue is damaged. Thus, compounds having IL-1 suppressive action and antioxidation action are believed to be useful not only as antiinflammatory agents, but also against autoimmune diseases such as chronic articular rheumatism and organ disorders such as those of the liver and brain that occur during ischemia.